Dundee manager Barry Smith called for clarity over the advantage rule after Jon Daly's penalty put the city derby beyond them as Dundee United claimed another 3-0 victory over their neighbours.

Daly was handed a second chance to beat Rab Douglas when referee Willie Collum penalised Gary Irvine for a foul on Stuart Armstrong after the Dundee United midfielder had cut the ball back for the Irishman to shoot into the goalkeeper's hands.

Daly made no mistake from the spot to put United two up in the 71st minute and Willo Flood wrapped up three Clydesdale Bank Premier League points in the latter stages when his weak effort bobbled over Douglas's arm.

Keith Watson had headed United in front against the run of play from a Barry Douglas corner in the 17th minute and Dundee striker Steven Milne volleyed over from 10 yards before having a strong penalty claim denied when his flick hit Brian McLean's arm.

Smith said: "I thought we started well. Obviously the first goal is a mistake. We started the second half well again but major decisions have gone against us.

"I think it has to be cleared up. There are too many grey areas and that's the problem. What's a penalty and when is it a penalty? When do you stop playing advantage?

"You can't let him shoot and then pull him back.

"It's either advantage or a penalty - it can't be both.

"We need to get that sorted out. We are having a meeting tomorrow and hopefully it can get ironed out."

Smith would not expand on the meeting but some SPL managers are due to hold talks with Scottish Football Association compliance officer Vincent Lunny on Monday to seek clarity over what they are allowed to say in the media.

Smith revealed he had not approached Collum for an explanation.

"No point," he said. "Some of them don't give respect back.

"Football's a heated game, they say we don't give them respect.

"Not all of them, there are a lot of good referees, but some of them don't give respect back."

Smith added: "That's major decisions gone against us. Up to that point in the second half we were probably in control and creating chances.

"They have won the game but did they deserve to win 3-0? I don't think so."

Peter Houston felt United's win was "thoroughly deserved" and also disagreed with his opposite number's view on the penalty decision.

He said: "I thought when you wipe someone out in the penalty box it's a penalty kick?

"Daly got a shot in but Armstrong didn't get the contact he wanted on the cross. He got wiped out.

"We have had it against us and today it went for us. The referee made the right decision and a brave decision."

Houston's team beat Dundee 3-0 in August in the first competitive Dundee derby for seven years and also triumphed by the same scoreline at Dens Park in a friendly in July.

"I think in recent games we have played better football but a derby match is all about winning and giving the supporters bragging rights," he said. "It was a professional performance. That's the third derby and it's three 3-0 victories so I can't ask for any more."